The field of the invention is in the art of aircraft collision warning systems, and more particularly that of an aircraft warning system that is mounted on aircraft and which has panoramic viewing for detecting light radiation emitted by other aircraft and objects, thereby indicating their presence.
The growing number of commercial and private aircraft using the air space has significantly increased the danger of midair collisions and has emphasized the need for an efficient, low cost aircraft warning system capable of alerting the pilot of an aircraft to the presence of nearby aircraft.
Warning systems in the prior art typically have included a transmitter and a receiver operating in the visible and/or infrared spectrum and operating together in a so-called "non-cooperative" system in which a pilot warning indication is given only when the receiver detects the radiation corresponding to the emitted radiation by its associated transmitters. Hence, a nearby aircraft from which a signal is not reflected adequately will pass undetected.
Furthermore, previously known aircraft warning systems have generally employed rotating radiation scanners driven by electric motors which generate electrical noise and interfere with aircraft communication and navigation equipment. The motor and its associated gearing are also apt to break down, and when the scanning mechanism fails, the entire warning system fails.
The present invention provides a self-contained aircraft warning system which operates in a passive and "semi-cooperative" manner to detect light radiations (ultra violet, visible or infrared) emitted by other nearby aircraft. Other warning beacons, such as those on antenna towers, will also activate the warning signal. It does not rely upon the detection of light emitted from its own beacon as reflected from another aircraft. It does require other aircraft to be equipped with a strobe beacon or rotating beacon warning system. The warning system disclosed herein is simple in design and requires no moving parts which might break down or interfere with other aircraft systems. U.S. Pat. No. 3,551,676 to patentee Runnels discloses a prior art passive system having panoramic viewing reflectors.
Typically, a multiplicity of detectors is provided for the panoramic viewing in a full 360.degree. circle of azimuth about a central axis. Each detector views a sector of the 360.degree. circle of azimuth. The number of detectors employed is based on the number of degrees of azimuth desired to be covered, and as dictated by the particular model of embodiment. The greater the number, the greater the discrimination in azimuth; also, the greater the complexity and cost. A means of optically masking the azimuth area of coverage, depending upon the model of embodiment, is also provided. This enables embodiments of the invention to be mounted in places where shielding from local radiation is required. Electrical means connected to the radiation detector, or detectors, give the pilot of the aircraft on which the apparatus is mounted, a warning when such radiation is received. Panoramic viewing with the multiplicity of detectors permits continuous viewing completely about the horizontal plane so that no mechanical scanning apparatus is required. Moreover, the particular arrangement of detectors taught herein is well adapted to the production of a wide range of aircraft warning indicators with panoramic fields of view having various angles of view above and below the horizontal plane. This last feature is particularly advantageous since the aircraft warning sensor will frequently be mounted in different positions and locations on different types of aircraft. Thus, the placement of a aircraft warning sensor, at the top of the vertical tail structure, would have an optical viewing pattern different from a warning sensor located under the aircraft's fuselage. Furthermore, the invention teaches the construction of a panoramic viewing structure that can advantageously be located at the outer extremities at each wing tip of the host aircraft, permitting a totally unobstructed panoramic view of 360.degree. of azimuth about the vertical axis in the horizontal plane of the host aircraft.
The use of more than one radiation detector in a given amount of bearing sector will provide an indication of the relative bearing of a detected aircraft within the sector. For example, four radiation detectors, each covering 90.degree., provide for the indication of the particular quandrant in the 360.degree. span relative to the aircraft heading in which the detected aircraft is located. The number of radiation detectors employed is a function of the desired number of areas in which detection is desired in a particular system embodiment. For example, 36 detectors will give an indication of each 10.degree. sector of arc relative to the aircraft's heading in which the detected aircraft is located.
Although the aircraft warning system of the present invention is primarily a receiver of radiation, one or more radiation sources can be advantageously combined integrally with the panoramic viewing structure when further means are provided for inhibiting the electrical alarm from responding to radiation emitted directly from such a source. In this arrangement, both radiation receiver and beacon are conveniently combined in one unit. However, it should be remembered that the present warning system is basically passive and does not rely upon the reception of radiation originating from the aircraft's own beacon. Indeed, special provisions are made to prevent the indicator from responding directly to radiation emitted by the aircraft's own rotating beacons or strobe systems.